Locating underwater wells



United States Patent 1111 ,5

[ Inventors Walter J- Bielstein; 3,027,951 4/1962 Knapp e161 175/10 R nl L- r.H .T X- 3,032,105 5/1962 Reistle 175/7X PP 623,974 3,160,85012/1964 Dudley 166/.5X 1 Filed April 1967 3,189,105 6/1965 Bates et al..175/5 Patented Dec-15,1970 3,191,695 6/1965 Bates et al. 175/5 AssigneeE850 Production Research p y 3,199,613 8/1965 114111666161. 175/53,215,202 11/1965 Pollard etal... 166/.5

3,222,634 12/1965 Foster 166/.5 1 1 LOCATING UNmjmWTER WELLS 3,336,5728/1967 Paul] @1111. 166/.5X

14 Claims, 1 Drawing Fig. P E a i er JamesA Leppink rzmary X m n [52]11.5. CI 166/.5, Asst-8mm Examiner Richard E. Favreau IN ll /QAttorneys-Thomas B. McCulloch, Melvin F. Fincke, John S.

E2) 47/00 Schne1der, Sylvester W. Brock, Jr. and Kurt S. Myers [50]FieldofSearch 166/.4, .5,

ABSTRACT: An underwater wellhead is located from a floating vessel byproviding a radiation source on the underwater [56] References Cltedwellhead and a radiation detection means in a drill string UNlTED STATESPATENTS lowered from the vessel such that the drill string is moved2,476,137 7/1949 Doll 166/4 respon ive t radi ion picke up y he e i n men to 2,545,179 3/1951 Voorhees.

engage the drill string with the wellhead.

LUBRICATOR lNDlCATOR PAIENIEI] DEC] 5 I976 LUBRICATOR INDICATOR V 27 ifI SHIELD RADIATION SOURCE lrvvmw 0R5. WALTER J. BIELSTEIN RONALD L.FOWLER,

1 LOCATING UNDERWATER WELLS BACKGROUND OF THE INVENTION 1. Field of theInvention The present invention is directed to locating a selectedlocation on water bottom. More particularly, the invention is conseismicand acoustic signals. lt has also been known to locate undergroundobjects by placing on or next to the underground objects radioactivematerial. Thus during the last war explosive mines were "located byradioactivity. It has also been known to mark fonnations pierced by awell bore with radioactive materials by firing bullets containingradioactive material into the wall of the well. However, the prior artfor locating underwater wells depend on an energy source which must bearranged on the wellhead to provide an acoustic or seismic signal.l-leretofore it has not been known and it is unobvious from the priorart to locate an underwater location such as an underwater wellhead byproviding a self-contained source of radiation on the wellhead. Thefollowing listed U.S. Pat. Nos. have been considered with respect to thepresent invention: 2,401,723; 2,545,179; 2,550,004; 2,728,554;2,770,736; 2,857,843; 3,103,976; 3,160,850; 3,179,176;

3,189,105; 3,191,695; 3,199,613; 3,215,202; and 3,222,634.

BRIEF DESCRIPTION OF THE DRAWING The present invention will be furtherillustrated by reference to the drawing in which the sole figure is aschematic showing of a preferred mode and embodiments.

DESCRIPTION OF THE PREFERRED MODE AND EMBODIMENTS Referring nowspecifically to the drawing, numeral 11 designates a body of waterhaving a drilling ship or vessel 12 floating at or adjacent water level13. Drilling ship'or vessel 12 may be any type of drilling vessel and itmay be one of the Seadrome type or a conventional type of ship suitablymodified for drilling operations. Although not shown, the drilling shipor vessel 12 may be supported suitably by buoyancy means located at asubstantial level below water level 13 such that the motion andmovements of the vessel 12 are not substantially affected by wind andwave action.

On the ocean floor 14 is a wellhead 15 having an upwardly facing conemember, cone means 16. It will be understood that wellhead 15 includesall auxiliary means usually associated with an underwater wellheadand'may include blow out preventor means, valves, flow lines, controlmechanisms, and the like. Arranged below the funnel means 16 are shieldmembers 17 containing sources of radiation 18 which are upwardly focusedto provide radiation beams which converge at a common point 19 as shownby the dotted lines. 7

The source of radiation may be a natural source of radiation having asuitably long half life to be effective. As examples of naturallyradioactive material may be mentioned by way of illustration and not byway of limitation:

Radium, 226 Uranium, 235 Thorium, 232 Plutonium, 239 Protactinium, 231Polonium, 210.

The source of radiation may also be artificially radiated material whichthen becomes radioactive. As examples of such materials may bementioned:

Beryllium Cesium Nickel, 63

Cobalt, 60

Zinc, 65

Sodium, 22

Rubidium, 103

Silver, 110

Cesium, 137.

When an artificially radioactive material is employed, it may be placedand shielded as indicated when a connection is made with the wellheadoriginally and then artificially radiated by exposure to a beam of highenergy neutrons which may be generated by an electrically powered devicelowered through the tubing string when the wellhead is initiallyinstalled or preferably the irradiation may be conducted before thesource is installed on the wellhead which allows this to be performed atwater surface or onshore as may be desired. In any event the radiationsource 18 is upwardly focused as shown.

Suspended from a derrick 20 arranged over a drilling slot 21 of thevessel 12 is a drill string 22 which is suspended from the derrick 20 bya cable or line 23 connected to the drill string 22 by suitableelevators or suspending means 24. A rotary table or-rotating device 10is embracingly arranged on drill string 22 for rotating same. The drillstring 22 carries on its lower end a drill bit 25 which maybe a rock bitof the cone type or a fishtail bit as may be desired. The drill string22 has at its upper end a lubricator device 26 for introduction intodrill string 22 of a radiation detecting means or sensor 27 which islowered into the drill string 22 by cable 28 which is run in over asheave or pulley 29 arranged in the derrick 20 and which connects to anindicating means 30. Connected to the lubricator 26 by a flexible hose31 is a pump 32 for pumping fluid into the drill string 22. The drillstring 22 may suitably be provided with a jet or nozzle 33 for jettingfluid laterally from the drill string 22. The drill bit 25 is suitablyprovided with nozzles or water courses not shown for circulation ofdrilling fluid during drilling operations but means may be provided toclose these nozzles when the radiation detecting means or sensor 27 is rat least 450 millicuries although lesser or greater strengths:

may be employed. The radiation source may have an intensity within therange from about 0.00001 to about 4500 Roentgens/hour at a distance fromabout 5 to about 0.03 feet respectively in fresh or sea water.

The radiation detecting means must be sensitive to the radiation havingan energy level of the source. Such radiation detecting means isavailable on the market and need not be described here.

In practicing the present invention the drill string such as 22 is runto within one joint, usually within about 30 feet of the wellhead 15.Equipment is assembled to run the radiation detecting means or sensorinto the drill pipe as illustrated. A

joint of drill pipe is made up and threadily attached into the top ofthe drill string 22. The sensing or detecting tool is introduced throughthe lubricator into the drill string and lowered into a position justabove the drill bit 25 as shown while the lower end of the drill string22 is within about 30 feet of the wellhead 15. Thereafter, the drillstring 22 is then lowered preferably to within about 5 feet or less ofthewellhead 15. The pump 32 is activated to provide a source of fluiduntil the level of radiation intensity begins to increase. The

drill string is rotated until the reading is at or near its maximum forthe particular position of the drill string 22 and the jet 33 may bediscontinued bystopping the pump or by closing a valve to close the jet33. Thus, the lower end of the drill string 22 is deflected horizontallyrelative to its point of suspension and rotated to cause the detectingmeans 27 to move relative to the source of radiation to obtain maximumintensity of detection for the particular position. The drill string 22is then lowered until radiation intensity on the indicating means 30reaches a selected maximum value. At this point the drill string 22 maybe lowered to or adjacent the ocean floor until the lubricator 26 isjust above the pipe slips (not shown) on the drilling vessel 12. Thejetting system will be closed at this point if not closed before. Atthis time the drill string 22 has engaged the cone 16 which allows thedrill string to be lowered through the wellhead l5 and into the well.The detection means or radiation sensor 27 may then be removed from thedrill string. The drill string 22 may be further lowered into the wellfor normal drilling operations. Alternately, this procedure may beperformed by adjusting the position of the ship to cause the drillstring to move laterally in a manner similar to the above procedure.

ln practicing the present invention the engagement of the wellhead bythe drill string 22 may be controlled automatically by computer meansnot shown. Once the wellhead 16 has been located such computer means mayalso maintain the drill string 22 in a position of maximum gamma rayintensity. Lowering of the drill string 22 may .be controlled eithermanually or by such computer means.

While the present invention has been described and illustrated inrelation to locating an underwater wellhead, it is susceptible tolocating any underwater location which has been previously marked withradioactive material which may be artificially introduced radioactivityor natural radioactivity.

The present invention is quite advantageous and useful in that it allowslocation of an underwater wellhead and reentry into the wellhead withoutdepending on outside sources of energy.

The nature and the objects of the present invention having beencompletely described and illustrated and the best mode and embodimentscontemplated set forth, what we wish to claim as new and useful andsecure by Letters Patent is:

We claim:

l. A method for locating an underwater wellhead from a floating vesselwhich comprises:

arranging on an underwater wellhead a radioactive material providing anupwardly focused source of radiation; lowering a hollow drill stringfrom said floating vessel until its lower end is at least in thevicinity of said wellhead; lowering in said drill string to a pointadjacent the lower end thereof a detection means for said radiationoperatively connected to indicating means accessible from water level;and moving said hollow drill string responsive to radiation picked up bysaid detection means from said source of radiation to engage said lowerend with said wellhead.

2. A method in accordance with claim 1 in which said source of radiationhas a strength of at least'SOQ millicuries.

3. A method in accordance with claim 1 in which the radiation source isgamma radiation.

4.A method in accordance with claim 1 in which said hollow drill stringis moved at least vertically and horizontally in any order.

5. A method in accordance with claim '1 in which the upwardly focusedsource of radiation is arranged to provide max imum radiation intensityalong a line coaxial with the wellhead.

6. A method in accordance with claim 1 in which:

a. the source of radiation is gamma radiation having a strength of atleast 500 millicuries; and

b. the hollow drill string'is moved at least vertically and horizontallyin any order.

7. A method in accordance with claim 6 in which the source of radiationis focused upwardly to provide maximum radiation intensity along a linecoaxial with the wellhead.

8. Apparatus for locating an underwater wellhead from a floating vesselwhich comprises:

a focused shielded radioactive source of radiation on said wellhead;

a hollow drill string dependingly carried from said vessel;

detection means for said radioactive source of radiation removablyarranged in said drill string adjacent the lower end of said drillstring;

indicating means on said vessel for said radiation; and

means for moving said hollow drill string responsive to said radiationpicked up by said detection means from said source of radiation toengage said lower end with said wellhead.

9. Apparatus in accordance with claim Sin which the moving meanscomprises:

a. means on said vessel for moving said drill string vertically androtatably; and

b. means adjacent the lower end of said drill string for moving samehorizontally. 10. A method for locating a selected location on waterbottom from water surface which comprises:

arranging at said selected location a radioactive material providing anupwardly focused source of radiation;

lowering a detection means for said radiation from water surfaceoperatively connected to indicating means accessible from water surfaceto the vicinity of said selected location; and

moving said radiation detecting means responsive to radiation picked upby said detection means to engage said detection means with saidselected location.

11. A method in accordance with claim 10 in which the detection means ismoved at least vertically and horizontally in any order.

12. A method in accordance with claim 10 in which:

a. the selected locationis an underwater well;

b. the radiation detection means is lowered in a pipe string dependinglycarried from water surface; and

c. the radiation detection means is moved vertically and horizontally inany order by moving the pipe string. 13. A method for locating anunderwater wellhead from a floating vessel which comprises:

arranging on an underwater wellhead an upwardly focused source ofradiation;

lowering a hollow drill string from said floating vessel until its lowerend is at least in the vicinity of said wellhead;

lowering in said drill string to a point adjacent the lower end thereofa radiation detection means operatively connected to indicating meansaccessible from water level;

moving said hollow drill string to deflect its lower end horizontallyand to detect said source of radiation with said detection means;

rotating said drill string responsive to radiation detected by saiddetection means from said source of radiation until a maximum level ofradiation intensity is indicated on said indicating means for theparticular position of the the lower end of said drill string; and

then moving said drill string vertically and horizontally in any orderas radiation intensity reaches a maximum intensity to engage said lowerend with said wellhead.

14. A method for locating a selected location on water bottorn fromwater surface which comprises:

arranging at said selected location an upwardly focused source ofradiation;

lowering a radiation detection means from water surface operativelyconnected to indicating means accessible from water surface to thevicinity of said selected location;

moving said radiation detection means to deflect it horizontally and todetect said source of radiation;

rotating said detection means responsive to radiation detected by saiddetection means from said source of radiation until a maximum level ofradiation intensity is indicated on said indicating means for theparticular position of the detection means; and

imum value to engage said detection rneans with said selected location.

